Chemical Tests!!!

Question 1

What is the chemical test for hydrogen?

Answer 1

Lit splint –> Squeaky pop!
(Combustion of hydrogen causes the test tube to resonate)

Question 2

What is the chemical test for carbon dioxide?

Answer 2

Limewater –> Turns cloudy
(Carbon dioxide reacts with limewater to make an insoluble white solid)

Question 3

What is the chemical test for oxygen?

Answer 3

Glowing splint –> relights
(Oxygen allows wood to combust more efficiently)

Question 4

What is the chemical test for ammonia?

Answer 4

Damp red litmus paper –> turns blue
(Ammonia reacts with dampness to form OH- ions)

Question 5

What is the chemical test for chlorine?

Answer 5

Damp blue litmus paper –> turns white
(Chlorine is a bleaching agent, and removes colour from the paper)

Question 6

How do you carry out a flame test?

Answer 6

1) Dip a piece of platinum wire into hydrochloric acid
2) Dip the wire into a sample of solid or solution
3) Place the tip of the wire into a non-luminous bunsen flame

Question 7

What colour is formed in a lithium flame test?

Answer 7

Red

Question 8

What colour is formed in a sodium flame test?

Answer 8

Yellow

Question 9

What colour is formed in a potassium flame test?

Answer 9

Lilac

Question 10

What colour is formed in a calcium flame test?

Answer 10

Orange-red

Question 11

What colour is formed in a copper flame test?

Answer 11

Blue-green

Question 12

How do you carry out a sodium hydroxide test?

Answer 12

1) Dissolve sample in water
2) Add a few drops of NaOH

Question 13

What precipitate is formed in a sodium hydroxide test with copper?

Answer 13

Blue, Cu(OH)2

Question 14

What precipitate is formed in a sodium hydroxide test with iron (Fe2+)?

Answer 14

Green, Fe(OH)2

Question 15

What precipitate is formed in a sodium hydroxide test with iron (Fe3+)?

Answer 15

Brown, (Fe(OH)3

Question 16

How do you carry out an ammonium test?

Answer 16

1) Dissolve the sample in water
2) Add some Na(OH) and warm it
3) Test the gas evolved with damp red litmus paper

Question 17

What colour will the litmus paper turn is ammonium is present in ammonium test?

Answer 17

Blue

Question 18

What is formed when ammonium reacts with sodium hydroxide?

Answer 18

A gas is formed

Question 19

How do we test for halide ions (Cl-, Br-, I-)?

Answer 19

Silver Nitrate Test

Question 20

How do we carry out the silver nitrate test?

Answer 20

1) Dissolve the sample in water
2) Add nitric acid
3) Add silver nitrate (AgNO3) solution

Question 21

What precipitate forms when chlorine reacts with silver nitrate?

Answer 21

White precipitate, AgCl

Question 22

What precipitate forms when bromine reacts with silver nitrate?

Answer 22

Cream, AgBr

Question 23

What precipitate forms when iodine reacts with silver nitrate?

Answer 23

Yellow, AgI

Question 24

How do we test for carbonates?

Answer 24

1) Add hydrochloric acid, look for effervescence
2) If there is effervesces, bubble gas through limewater

Question 25

What is the chemical test for water?

Answer 25

Water + anhydrous copper sulphate (CuSO4)
Goes white –> blue

Question 26

What is the test for waters purity?

Answer 26

Measure its boiling point and compare it to 100°C, the closer to 100°C, the more pure